I have sync'ed multiple collections from LR Classic to LR CC over the past couple of months. Recently I noticed that the space used is not changing even though I have added several thousand photos. (Space used is seen in LR CC after clicking on the "cloud" icon in the upper right corner of the LR CC desktop app.) The photos sync just fine. I can view them on LR CC on any device including the web. My concern is that I am using more space than is being reported. How can check to make sure the space used is correct?

OK. That makes sense. So, if I want to use a combination of LR Classic and LR CC and have a copy of the original files locally and in the cloud, what is the best way to do that? Do I actually have to import the files into to each app separately? If so, then it seems I lose the ability to keep the changes sync'ed.

If you set Lightroom CC up properly, it will store images on your local hard drive as well as in the cloud. That is all I can tell you because I don't use Lightroom CC. But by answering your question, hopefully it will keep this conversation active and some of the other experts with Lightroom CC will be able to give you more information.

OK. That makes sense. So, if I want to use a combination of LR Classic and LR CC and have a copy of the original files locally and in the cloud, what is the best way to do that? Do I actually have to import the files into to each app separately? If so, then it seems I lose the ability to keep the changes sync'ed.

Yes you do have to import the files into each app, but no you won't lose the ability to keep the changes synced. The way you can achieve this is by first syncing your images from LR Classic, thus putting Smart Previews into the cloud. When that is done, you can then import the same images into the LRCC desktop app (or LRCC Web). LRCC recognises that the images are already synced as Smart Previews, but it goes ahead and uploads the full original to replace the Smart Preview. The image is still synced in LR Classic, except it's now aware that the original has been uploaded, so all ongoing edits etc will continue to sync.

But be aware that a combined Classic and LRCC workflow with full originals uploaded isn't recommended by Adobe, and also that not everything syncs (e.g. keywords and location data don't). I find it incredibly useful to have my images in the cloud, which I access mainly through LRCC Web and LRCC for iOS on my phone and tablet, but Classic is still the centre of my workflow. Other than doing the upload of originals, I rarely use LRCC on my desktop.

I think that is exactly what I am looking for. If I understand correctly, the workflow would be to import original to LR Classic, create a collection and sync with LRCC, then open LRCC and upload originals to cloud. I am curious as to why Adobe would not recommend that workflow? It would seem useful (as you say) but also provide back up of the original photos.

A variation that I would like to use as well is when working remotely; import originals to LRCC using a laptop, edit on location, then when back at the desktop, sync with LR Classic. Any thoughts on how to sync with Classic when the original import is in LRCC?

Provided you have the Classic catalog enabled for syncing, ANY image that you add into any of the LRCC apps will automatically be synced down into Classic, full original, and stored in a default location which you can change in the Classic preferences. So, take a picture on your phone, start LRCC on the phone (or better yet, use the LRCC camera on the phone), the image syncs to the cloud. When you next start Classic the image is downloaded automatically. That functionality has been available for about 4 years...